A separable transformer, including primary and secondary cores disposed opposite to each other, has a function of transmitting signal or energy between the cores in a contactless fashion by means of electromagnetic coupling. Especially, a rotary-type separable transformer, called a rotary transformer, including a stator core and a rotor core (primary and secondary cores) respectively mounted to a stationary member and a rotary member rotatably supported by the stationary member, is widely used in various applications. In general, a separable transformer (rotary transformer) of this type is provided in the form of a one-piece module that is comprised of primary and secondary cores (stator and rotor cores) assembled in advance into one piece, with these cores disposed opposite to each other. For instance, the modularized separable transformer (rotary transformer) is incorporated into an automotive steering unit and serves to transmit explosive energy of an air bag apparatus mounted to a steering unit or transmit a signal to a cruise control unit.
The assemblage of an automotive steering unit is generally performed in a final assembling stage in a main assembly line where an instrument panel, a console box, a seat and the like are mounted to a vehicle body. Thus, a space available for the assemblage of a steering unit is largely limited. Under such circumstances, an operator is obliged to keep a hard posture during the operation of mounting a separable transformer to a steering unit and electrically connecting primary- and secondary-side component parts of the separable transformer individually to electric circuits of a shaft module (stationary member) and a steering wheel module (rotary member).
In the case of a separable transformer comprised of primary and secondary-side component parts that can be assembled in advance separately from each other, it is conceivable that the assemblage of the separable transformer may be made at the same time when the separable transformer (rotary transformer) is mounted to a steering unit. In this case, however, the separately assembled primary- and secondary-side component parts must be incorporated into the steering unit with a considerably high degree of assembling precision. Further, it is very difficult to precisely align axes of both the primary and secondary cores (stator and rotor cores) of the separable transformer (rotary transformer) with each other and to set the distance (gap length) between the opposed cores with high accuracy so as to permit the separable transformer to exhibit intended capabilities.
The present invention has been accomplished in view of the above circumstances, and it is an object of the present invention to provide a method capable of assembling a separable transformer with improved workability.
Especially, an object of the present invention is to provide a method of assembling a separable transformer, which makes it easy to carry out electric wiring operations for primary- and secondary-side component parts of the separable transformer.
Another object of the present invention is to provide a method of assembling a separable transformer, which is capable of precisely setting a positional relationship between a primary core and a secondary core by a simple operation procedure.